This invention relates to vehicle suspension adjustment systems, and in particular, to a self-contained system for adjusting both camber and caster.
Conventional vehicle suspensions include devices for adjusting the position of suspension control arms to control wheel camber and/or caster. One conventional system for adjusting wheel camber includes a mounting bolt that extends in a fore-aft direction of the vehicle through a suspension control arm and a pair of support members of a vehicle frame disposed on either side of the control arm. The support members include elongated slots configured to allow movement of the bolt along a transverse axis perpendicular to the longitudinal axis of the bolt. Cams are disposed proximate either end of the mounting bolt and move in grooves defined in either the support members of the vehicle frame or retaining plates attached to the support members. Rotation of the cams causes movement of the bolt along the transverse axis and enables adjustment of wheel camber. This adjustment system, however, does not enable adjustment of wheel caster.
Another conventional system for adjusting both wheel camber and wheel caster includes a mounting plate that extends in a fore-aft direction of the vehicle between the eyes of a bifurcated suspension control arm. The system further includes two bolts extending transversely to the direction of vehicle travel and into the mounting plate. Shims are supported on each bolt. Adding or removing shims on either bolt enables adjustment of wheel caster. Adding or removing equal numbers of shims from both bolts enables adjustment of wheel camber. Although this adjustment system enables adjustment of both wheel camber and caster, the system suffers from several other disadvantages. First, the system requires a relatively large amount of time to make desired adjustments. Second, caster adjustment cannot be entirely independent of camber adjustment, since the addition or removal of shims from one bolt necessarily affects the camber of the wheel. Third, the system requires storage and maintenance of the shims.
There is thus a need for a suspension adjustment system that will minimize or eliminate one or more of the above-mentioned deficiencies.
The present invention provides an improved suspension adjustment device.
A suspension adjustment device in accordance with the present invention includes a fastener disposed about a longitudinal axis. The fastener extends through a slot defined in a first support member of a vehicle frame, a control arm, and a slot defined in a second support member of a vehicle support frame. The inventive assembly further includes a first cam disposed about the fastener and disposed within a groove in the first support member of the vehicle frame. The inventive assembly further includes a second cam disposed about the fastener and disposed within a groove in the second support member of the vehicle frame. The inventive assembly finally includes means for adjusting the position of the control arm relative to the vehicle support frame along the longitudinal axis of the fastener. In one embodiment of the invention, the adjustment means comprises one or more shims disposed about the fastener between one of the support members of the vehicle frame and the control arm. In another embodiment of the invention, the adjustment means comprises a threaded bushing that is disposed about the fastener and disposed partially within the control arm. The rotation of the bushing adjusts the fore-aft position of the control arm, thereby adjusting wheel caster. Rotation of the first and second cams causes movement of the fastener along a transverse axis perpendicular to the longitudinal axis of the fastener, thereby adjusting wheel camber.
A suspension adjustment device in accordance with the present invention has several advantages as compared to conventional suspension adjustment devices. The suspension adjustment device of the inventive assembly combines both camber and caster adjustment in one control arm mounting system. The inventive device also uses a single fastener to attach the control arm to the vehicle frame. This simplifies the adjustment of the control arm and wheel camber because both the forward and rear portions of the control arm move together when adjusting camber. The inventive device further provides, in one embodiment of the invention, for the interchange of shims during adjustment so that the sum total of shims remains constant before and after adjustment and there is no need to store or maintain the shims. Finally, in one embodiment of the invention, the inventive device clamps the suspension control arm to one of the vehicle frame support members while allowing the control arm to float relative to the other support member. This allows the use of low ductility material for the support member, such as heat treated aluminum.